To improve the resolution of protein separation, ultrafiltration swing (periodic backflushing) was introduced to the membrane ultrafiltration process. Hemoglobin and dextran were used as model compounds. Increase in mass transfer coefficient with ultrafiltration swing was theoretically predicted.
Filtration and separation performance, defined by apparent permeability and retention coefficient of dextran respectively, were measured to determine the effects of concentration and recirculation rate. Higher concentration and lower reciculation rate decreased membrane performance.
The membrane performance was improved with the increase in frequency of backfflushing and duration of backflushing per one cycle of ultrafiltration swing. The maximum increase was 2.8 folds in filtration performance and 1.5 folds in separation performance respectively. Also this method was applied to the membrane recycle bioreactor with yeast cells by comparing the filtration efficiencies of the cells with and without ultrafiltration swing. The membrane permeability with ultrafiltration swing increased considerably than that without swing. In addition, several operation modes inducing flow swing are suggested.